The Policy and Charging Control (PCC) architecture and functionality is specified in 3GPP TS 23.203 (v.11.7.0) for Evolved 3GPP Packet Switched domain, including both 3GPP accesses (GERAN/UTRAN/E-UTRAN) and Non-3GPP accesses.
Conventionally, and for the purpose of the present invention, the Policy and Charging Control (PCC) architecture includes a Policy and Charging Enforcement Function (PCEF) in charge of traffic flow detection and enforcement of applicable policies to user traffic flows, a Policy and Charging control Rules Function (PCRF) in charge of providing network control for the traffic flow detection by holding policies and providing PCC rules to the PCEF per user traffic flow basis for enforcement of such policies, and a Subscription Profile Repository (SPR) in charge of providing subscription data for a user to the PCRF.
In particular, the PCEF is a functional entity which may be incorporated, for example, in a Gateway (GW) node providing IP access to the Packet Data Network (PDN), hereinafter the PDN-GW, or in a Gateway GPRS Support Node, hereinafter the GGSN, or which might be provided as a standalone entity.
A so-called Gx reference point is defined in 3GPP TS 29.212 v11.6.0 as the interface between the PCRF and the PCEF, whereas a so-called Sd reference point is defined in 3GPP TS 29.212 v11.6.0 as the interface between the PCRF and the SPR.
In particular, instead of the SPR, the PCC architecture may include a User Data Repository (UDR) communicated with the PCRF via the so-called Ud reference point as disclosed in 3GPP TS 29.212 v11.6.0.
The Gx reference point is used for provisioning, modification and removal of PCC rules from the PCRF to the PCEF and for the notification of traffic plane events from the PCEF to the PCRF. This enables the PCRF to make PCC decisions and have dynamic control over the PCC behaviour at a PCEF, which is the enforcement point.
Regarding the provision of conventional PCC rules, two procedures exist to provide conventional PCC rules by the PCRF: PULL procedure (provisioning solicited by the PCEF) and PUSH procedure (unsolicited provisioning). The PULL procedure typically occurs at default bearer establishment, i.e. during a User Equipment (UE) Attach procedure, when the PCEF initiates establishment of a session with an IP Connectivity Access Network, hereinafter an IP-CAN session, by sending a CC-Request message over the Gx interface. The PUSH procedure occurs in response to information provided to the PCRF via a so-called Rx reference point, also specified by 3GPP, or in response to an internal trigger within the PCRF.
In both cases, the PCC rules provided by the PCRF apply to a particular IP-CAN session, which is associated with a particular UE. The PCEF shall indicate, via the Gx reference point, a request for PCC rules at IP-CAN session establishment, modification and other events. If there is no PCC rule active for a successfully established IP CAN session, the PCEF shall initiate an IP-CAN session termination procedure.
The PCC rule contains, among other elements, one or more service data flow filters, quality of service (QoS) information and charging parameters. The service data flow filters identify the data traffic for which the PCC rule applies, in both uplink and downlink direction, and whether the traffic should be allowed or blocked. The QoS information identifies the performance characteristics of the data flow, which determines the network resources required to transport the service. Finally, the charging parameters include the rating group and other information for credit control and interfacing with online/offline charging systems. With this information, the PCEF can encompass service data flow detection, policy enforcement and flow based charging functionalities.
On the other hand, each UE subject to PCC procedures is provisioned in the SPR. The SPR contains all subscription related information needed for subscription-based policies, and for generation of PCC rules by the PCRF. The SPR can be internal or external, and may be combined with or distributed across other databases in the operator's network. In particular, the SPR may be combined with a Home Subscriber Server (HSS) of the IP-CAN network to form a user database system of the operator's network, or may be provided as an integral part of the aforementioned UDR.
Even though there is a clear consensus in the industry on that mobile Machine-to-Machine (M2M) type communications will play an increasingly prominent role in carrier networks and IT operations, 3GPP TS 23.203 only provides for control of individual devices.
The provision of policy and charging control for millions of M2M type communications (MTC) devices is a challenging task for mobile communications networks. In principle, the MTC devices are expected to be treated as standard mobile subscribers that need to be provisioned and policy-controlled individually. However, applying policy and charging control in scenarios where a huge amount of MTC devices is supported presents a number of drawbacks for the currently existing PCC procedures, such as but not limited to: the amount of data to be stored in subscriber databases and the access rate, the signalling load on the Gx interface, and the processing capabilities of PCRF and PCEF nodes.
For the purpose of the present specification, subscription related information and subscription data, as well as subscriber related information and subscriber data, they all are equivalent terms unless a particular difference or clarification is explicitly cited in a relevant passage. Likewise, the terms ‘user’, ‘UE’, ‘MTC device’, ‘device’ or even ‘subscriber’ may indistinctly be used throughout this specification unless a specific different term is unambiguously inferred from the context or explicitly cited in a relevant passage.
On the other hand, 3GPP TS 22.368 states general group based requirements and group based policing in order to optimize procedures on MTC devices. That is, there is a need generally required for introducing and developing the grouping of MTC devices in order to facilitate the handling of MTC devices for network operators.
However, as already commented above, 3GPP TS 23.203 only provides for control of individual MTC devices and, consequently, there is a need to develop and adapt the currently existing PCC procedures in order to support a huge amount of MTC devices.